The present invention is directed to a device for handling tools used to separate blanks in a machine processing plate or sheet-shaped workpieces for producing blanks for forming packages.
In order to form a package three successive phases must be accomplished. These are:
Printing numerous motifs or images on a sheet of material with each motif or series of images representing a single package; PA0 Cutting the sheet into several blanks, each of which is printed with the motif; and PA0 Folding and gluing every blank with a view to form the flat folded package.
The sheet after having undergone the cutting action is transferred as a rule by means of gripper bars which are mounted on a pair of chains to a subsequent waste stripping station wherein waste which consist of the portions of the sheet area situated between every blank and which is to be excluded from the package is removed. After passing through the stripping station, the sheet with the waste removed is sent to a delivery station with all the blanks of the same sheet remaining attached together by means of linking points which correspond to very small non-cutting nicks, which were made in the cutting rules of the press which perform the cutting.
In the delivery station, and depending on the requirements, it should be possible to either form a pile of the sheets with all of the blanks in each sheet still being attached to one another by means of their linking points or to simultaneously form several piles of blanks which have been separated from one another due to the breakage of the linking points which occurs in a previous station called a blank separating station.
In a blank separating station, it is the current practice to use an upper movable and a lower fixed tool. The upper tool consist of an assembly of punches and the lower tool is a matrix with apertures. The upper movable punches will force the blank through the apertures in the lower matrix which causes the breakage of the various linkage points either between each blank or between the margin of the blank and the peripheral waste of the sheet. The separating tools will thus have to be adapted to the shape and the arrangement of the blanks on each new run of sheets which are being processed. Generally the punches are positioned according to the cutting lines of the press on a basic plate fitted on an upper movable tool carrier frame and the blank separating station. A corresponding aperture or mesh of the over matrix is made up of little bars and are situated underneath and aligned with every punch. The little bars are arranged so as to overstep one another to form a grid or matrix of which the meshes have approximately the same dimensions as the blanks which are to be separated.
In order to avoid manufacturing new blanks separating tools for every new run, it has been suggested in U.S. Pat. No. 4,175,686, whose disclosures incorporated by reference thereto and which claims priority from the same Swiss application that matured as Swiss Patent No. 617886, to fit the punches to be horizontally shifted along bars mounted on a vertically movable frame. In addition, the lower matrix consist of crossed bars which are shiftable in such a way as to form a grid of which the meshes or size of the openings have adjustable dimensions. For its preparation the lower tool is placed flat upon a table covered with a sheet having an imprint representing the blanks on the sheet. Then, the bars are positioned with reference to the imprint. The preparation of the upper tool is more or less similar with the difference that not only are the bars being positioned but also the punches are shifted along the bars with regard to the imprint. However, when the upper tool has the shape of a plate with air outlet openings and the punches are mounted on the lower surface of the plate in a removable way, the above-mentioned procedure will not be usable. In fact, it is difficult to perceive the imprint through the plate openings, yet the use of such a plate is increasing.
In addition to reduce the machine production stops to a maximum amount, it is current practice to prepare on a first table the upper and lower tools for a subsequent run. At the instances of a required tool exchange, the operating tools are slid out of the machine on to a second table which is positioned adjacent the machine. Then the second table is moved and the first table is positioned in the previous position of the second table so as to allow the new tools to be slid inside the machine. The substitution of one table by another is troublesome and increases the down time necessary for changing the tools. In addition, the two tables which are needed increase the amount of space necessary in the general vicinity of the machine.